width = 10;
longth = 16;
height = 40;
thickness = 4;

translate([0, 0, height/2 ]) {
    difference() {
        cube([longth + thickness,
                width + thickness,
                height], center = true);
        cube([longth,
                width,
                height], center = true);
        translate([0, width/2, 4]) {
            cube([longth, thickness, 16], center = true);
        }
    }
}

translate([0, 0, 8 / 2]) {
    cube([2, width, 8], center = true);
}
/*
   translate([0,0, thickness/2 + thickness]) difference() {
   gap = 0.8;
   cube([longth + thickness + gap,
   width + thickness + gap,
   thickness], center = true);
   cube([20, 20, thickness], center = true);
   }
 */
